Funny how the discussions turn... I just finished the preliminary tweaking and voicing on this 2 stage volume-only amp, which I started building almost 2 years ago. It does cost more than $100 but it's just what I've needed for a small amp.

The idea was to re-do the basic Champ circuit using parts I had on hand; EF804 input, 807 output, 500V power transformer, and a Doberman OPT. It ended up about 2X the output capability of the Champ and I'm using a 12" speaker so I call it Da Crusher.

I switched to a choke input to get about 440V B+ for the 807, which results in a super quiet amp. Just a little EMI buzz with the gain wide open!

I started with values based on the Champ and got really lucky on the voicing first time out. Currently using a 12" 50W ceramic speaker in an open baffle (Fender HRD box) and it sounds nicely balanced. The guitar controls and the second input jack at -6db give me a wide range of tone. It's mostly clean with a nice smooth crunch as I dig into my hot pickup. I can't think of anything constructive to do with the voicing now, but plan to try a low wattage alnico 12" in both open and sealed cabs. I also have an Altec 421 15" I want to try for grins.